Electric-arc lamp



2 Sheets-Sheet 1.

(No Model.)

B THOMSON ELECTRIC ARC LAMP.

No. 493,739. Patented Mar. 21,1898.

WITNESSES ATTORNEY (No Model.) 2 Sheets-Sheet 2.

E. THOMSON.

ELECTRIC ARC LAMP. No. 493,789. Patented Mar. 21, 1893.

WITNESSES IN V NT 01? %p%% %%6/ 6 Wad m 7/ M- BY A TTORNE Y UNITEDSTATES PATENT CEEicE.

ELIHU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON- HOUSTONELECTRIC COMPANY, OF CONNECTICUT.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part Of Letters Patent N0. 493,739, dated March21, 1893.

Application filed June 30. 1886- Serial No. 206,676. (No model.)

To aZZ whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of .ti e'United States, anda resident of Lynn, in the county of Essex and State of Massachusetts,have invented a certain new and useful. Electric-Arc Lamp, of which thefollowing is a specification.

My inveiition relates to certain improvements in electric arc lampmechanism designed to render the lamp more efficient in action infeeding the carbons, cheaper to construct, and easier to adapt to variedconditions of working.

My inventitn relates more particularly to means forimparting a step bystep feed movement to the carbon to compensate for consumption.

The invention consists also in a novel means for imparting first, alifting movement to the carbons for the purpose of forming the arc andthen by the same mechanism producing an intermittent step by step feedmovement each of whose steps may be of any desired length.

In some of its features my invention may be regarded as an improvementupon that shown in United States Patent No. 256,605, dated April 18,1882, inasmuch as it embodies feed clamps 0r clutches having adifference in their range of movement, which clamps or clutches arecontrolled by a lifting and feeding magnet placed in the main circuitand periodically cut out of circuit by means of a shunt or derivedcircuit to the are, when afeed of the carbons is required to take place.The improved lamp however forming the subject of my present applicationcontains an improved differential clamp movement and alsoinvolves theemployment of asecond switch contactin the branch of circuit by whichthe main circuit magnet is cut out or de-energized. Such second contactis designed to interruptsuch cut out branch or de-energizing circuitintermittently, and is preferably operated by the main circuit magnetitself.

I will first proceed to describe a lamp constructed in accordance withthe above principles and embodying in addition other features ofadvantage to the general operation of the lamp, but which are sometimesdispensed with, and will then in the claims more particularly recite thenovel combinations and features constituting the invention.

In the accompanying drawings illustrating a lamp containing theinvention herein claimed; Figure 1, is a side elevation of the lamp.Fig. 2, is a diagram of the circuitconnections. Fig. 3, is a sideelevation of difierential feed clamps or clutches for the carbon rod orholder. Fig. 4, is a plan view of the same. Figs. 5 and 6, show thedifferential clamps or clutches in the two positions which they assumeduring action. Fig. 7, illustrates in side elevation a modified form ofthe clamps. Figs. 8 and 9, illustrate modified forms of contact devices.Fig. 10, illustrates in side elevation a modification in the feedingclamps, designed to secure additional advantages. Fig. 11, shows amodification similar in its operation to that of Fig. 10. Fig. 12, is alongitudinal section of a lower or negative electrode adapted for usewith currents of small volume. Fig. 13, is a longitudinal section of thefeed magnet connected to the feeding clutches. Fig. 14, illustrates amodification in which a separate magnet is used for forming the are. IFig. 15, illustrates a modification in the manner of mounting andarranging the two contacts which control the shunt or de-energizingcircuit of the feed magnet.

Referring to Fig. 1, E, indicates the posi- Live or upper carbon orelectrode, which may either be clamped toacarbon supporting rod as usualin the art, or may itself be fed directly through the clutches, thecarbon holding rod being dispensed with.

J, J, indicate clamp shoes or clutches of any desirable materialpressing against the carbon rod or holder at opposite sides thereof insubstantially the same transverse line. The shoes or clutches areconnected to their operating lever L, by links as shown attached to thelever at different points from the fulcrum 19, thereof, borne by theframe of the 5 lamp. The clutches are pressed against the rod by theact-ion of a spring .2, uniting the links. By this construction theclamp shoes or clutches are given a diiferent range of movement on therise and fall of the lever IOO produced through the action of an electromagnet M, which is provided with a movable armature, or a core O,connected to the lever, so that, when the lever is raised by the actionof coils of the magnet, the clutches will be raised and move the carbonrod upward.

The magnet M, has its coils in the circuit of the lamp as indicated fromthe point X, to the carbon holder and arc.

K, indicates a derived circuit magnet of any suitable constructionplaced in a branch or derived circuit around the arc and serving tocontrol the position of a switch contact Q, which is carried by thearmature N, of the electro magnet and is suitably arranged withreference to a contact stop so that, when the armature is moved by thepower of the magnet, the contact will close circuit.

A retractor S, for the armature lever of the derived circuit magnet issuitably adjusted so that, unless the resistance of the are slightlyexceeds the normal, the contact will not be pulled down to close thecircuit.

The contact Q, serves as one of the contacts controlling a branch orde-energizing circuit for the electro magnet M, so that when the contactis closed, the magnet M, will lose its power and its armature L, willfall back. This ole-energizing circuit is here shown as consisting of abranch around the electro magnet M, which can only be completed when thelever L, is raised. In this branch or shunt path is interposed a secondcontact indicated at T, which is carried by the lever L, or is otherwisearranged so that, when the lever L, is lifted, the shunt branch orcircuit may be completed if at the same time the contact Q, is closed,and when depressed by the falling back of the lever, the shunt orde-energizing branch shall be open. For the purpose of closing thebranch the contact T, makes connection with a suitable stop R. One ofthe contacts, as for instance contact T, is so mounted as to be ayielding or movable contact capable of movement independently of thearmature lever, the effect being to permit the armature to move a littledistance after contact is established, and on its reverse movement tomove slightly before contact is broken. The contact is preferably madeas a spring. By this device the operating lever is permitted to have arange of movement beyond that necessary for merely opening and closingthe contact.

Instead of providing a separate stop for each of the two contacts T, Q,as shown in Fig. 1, each contact may form a stop for the other with thesame resultant effect, as illustrated in Fig. 15. In this instance thecontact R is moved by the magnet K, through a very limited range, whilethe contact T, is moved upward toward the stop or contact Q, through arange limited by a stopf. When the armature N, of magnet K, is retractedby a spring S, the contact Q, is held in position where the contact T,cannot reach it so as to close the branch or d'eenergizing circuit, butwhen the magnet K, overcomes the retractor, the contact Q, is drawn downso as to close circuit on the contact T, until, throughthe action to bepresently described, the feed has been sufficient to permit theretractor S, to again draw the contact Q, out of range of T, thusbreaking the de-energizing circuit and permitting the magnet M, to holdthe lever L, up.

The lower electrode E, may be of carbon, or in some cases as where verysmall currents are used it may consist of a cone of copper tipped withan iridiumpoint which does not waste during burning of the lamp.

The circuits of the lamp will be readily understood from the diagram.The connections are made by any desired devices.

Entering at X, the current divides, one portion passing through thecoils of M, to the carbon rod or holder and through the arc to the pointY. A very small fraction of the current passes around the are throughthe high resistance of the coils in magnet K. \Vhen the contacts T, Q,are closed a portion of the current flows in a branch around the coilsof magnet M, re-uniting with the current which flows through the latter.\Vhen no current flows, the branchcircuit is open at the contact T,because the lever L, is down. The clutches J, J, are depressed and thecarbons are in contact, the armature N, is retracted and the contact Q,is open. When current passes, the electro magnet M, is energizedinasmuch as its de-energizing circuit is open and lifts the lever L,thusraising the clamps or clutches J, J, but at different rates. The springZ, holds the clamps against the carrier with sufficient friction toenable them to lift the carbon E, so as to form the arc. As the lever L,and the armature, or core 0, continue to rise, the contact T, closescircuit at its stop with an elastic pressure, the spring T, bendingslightly so as to allow the core and lever to rise somewhat beyond thepoint of closure. This action does not shunt the magnet M, inasmuch asthe contact at Q, is still open. The are now burns until its re sistanceis sufficient to cause the magnet K, to close the contact Q, by whichaction the magnet M, is shunted or weakened owing to the establishmentof the de-energizing circuit through the contact Q, and the contact T.The coreC, now falls away allowing the lever L, to move downwardcarrying with it the clutches J,J, the clutch J, moving downward fasterthan clutch J, owing to the fact that it is connected to the lever at agreater dis tance from its fulcrum. If now the clutch J, be suitablyconstructed to have a greater friction or bite on the carbon holder itwill move the rod downward past J. In most cases the friction or bite ofthe two clutches may be equal if the weight of the carbon holder isconsiderable, but otherwise the clamp J, should be given a greater bitewhich may be accomplished readily by making the spring pressure holdingit against the rod greater, or constructing it so that it shall have agreater surface in contact with the rod. The same result will beaccomplished by making the surface of J, from a material having greaterfriction on the rod, or by connecting it with the lever through a linkapplied in such way as to bear upon the clutch more nearly at a rightangle. In any such case the rod will be fed downward, the adjustmentbeing made such that a vibratory movement of the lever L, up and down,will feed the rod through the difference in range of movement of the twoclamps in a similar manner to the devices described in United StatesPatent No. 256,605, before referred to. As soon as the lever L, dropsback to a point where the contact T, opens the shunt or de-energizingcircuit for the magnet M, the latter is again energized and raises thelever so as to again complete the shunt or de-energizing circuit throughclosure of contact at T. This action is repeated and continued, giving avibratory movement to the lever L, as long as the contact Q, remainsclosed. But as the vibration is attended by a feed of the carbons theare soon becomes shorten ed to its normal length and the armature N, isreleased thus opening contact at .Q, so that the next time the lever islifted to close contactT, the shunt or deenergizing circuit is notestablished, and the lever L, therefore remains lifted with the contactT, closed, ready for a repetition of the described operation.

In Figs. 3 and 4, an additional spring Z, is shown connected with thelink applied to lever J, so as to give the latter a greater friction orbite upon the carbon rod. Thelower portions of the shoes or clutches J,J, are preferably tapered outward to permit the carbons to be insertedfrom below. This construction is also preferably employed where thecarbon is fed directly by direct engagement of the clutches or shoeswith it.

In Figs. 5 and '6, the effects produced by moving the lever L, areillustrated.

In the modification shown in Fig. 7, the clutches or shoes J, J, aredirectly pivoted to the lever L, and have independent springs Z, Z,connecting them elastically to the frame F, the spring Z, beingpreferably a little stronger than Z, especially where the carbon sticksor pencils areto be fed directly.

It is not essential that the contact T, should be a spring contact orthat the lever L, may have a movement in excess of that required forsimply opening and closing the circuit. Any devices may when founddesirable be employed which will suffice to give the lever L, anadditional movement beyond that which would ordinarily be attendedbysimply bringing the contact against its stop and away from the same.For instance a device such as shown in Fig. 8, may be employed for thesame purpose. This device consists of a magnet T, pivoted on lever L,and having a limited free movement at its contact end which movement isdetermined by suitable stops m, m, as indicated. The stop R, forming inthis case the contact stop consists of an armature or piece of soft ironthat is attracted by the magnet T. When the lever L, rises, the magnetT, closes the circuit through the magnetic attraction a little beforethe lever L, has completed the upward movement allowed to it, and whenthe lever L, falls away, the magnet T, hangs to R, until the left handstop m, takes up all play of the lever T, and pulls it oif of the stopR. Another equivalent device adapted for employment in the same way isindicated in Fig. 9. In this case T, is a blade spring bearing a verysmall electro magnet t, which is put into circuit when it closes uponthe stop R, during upward movement of the lever L. The contact and itsstop are thus held together, B, being of magnetic material, and thespring T, upon the descent of the lever L, being held at its free end isbent until a stop V, carried by the lever bears upon it and forces thecontact off of its stop.

In Fig. 10, I have shown clamps or clutches which are preferablyemployed where the clutches are required to work upon the carbon holdingrod of metal. These clutches are so arranged that when lever L, iscompletely down, the carbon rod or holder shall be entirely free todescend by gravity. The clutches herein shown consist of a clutch bodyembracing the carbon rod and supported upon or pivoted to the lever L.Hinged to the clutch body is a clamping jaw or lever having an extendedarm to which a spring is connected in such way as to tend to make thejaw bite upon the rod. A fixed stop arranged in the path of the armreleases the jaw from the rod when the clutch body is moved in theproper direction. These clutches are of the same general constructiondescribed in many prior patents granted to me. The upper clutch J, asshown,

is connected to the lever L, near its pivot or fulcrum p, while thelower clutch J, is 0011- nected to the lever at a greater distance fromthe fulcrum. The lower clutch J, is however inverted in position asshown. A spring Z tends to close the pivot jaw or clutch upon the rod,while an extension (1, from the clutch lever is arranged so as to engagewith a stop I), and open the clutch when it is depressed. A similar stopa, serves to open the upper clutch J. When the lever L, is down in itslowest position the clutches are both opened by their respective stops aand b, but when the lever is raised the clutch levers are moved awayfrom their stops and the springs Z, Z, cause the clutch jaw to grip thecarbon rod or carrier. It is plain that in this movement the clutch J,will have the advantage of grip due to the fact that the weight of therod tends to pull its clamping jaw against the rod, while in the case ofthe clutch J, whose clam ping jaw is inverted,there is no such tendency.The range of the clutch J, will therefore determine the extent of lift,if the spring Z, be so weak as not to give the clutch J, a greater biteduring such upward movement.

The clutches must be constructed to act by friction only, and not to jamtightly. This is secured by constructing the clamping jaws so that theyshall bear on the rod not too near the point where ahorizontal line,drawn from the fulcrum of the jaw strikes the rod, that is to say, theline drawn from the pivot of the clutch to the point where the clutchbears on the rod must make a considerably less angle than a right anglewith the axis of the rod. When the lever L, descends, the clutch J, willmove faster, and the spring Z, being made stronger than Z, the rod willbe pulled downward through the clutch J, by the action of the clutch J,and will be fed as in Figs. 1 and 2, step by step, through theintermittent or vibratory up and down movement of the lever L.

.In the modification shown in Fig. 11, the clutches are of the ringclamp type. They must be arranged and constructed so that they shalltilt to a greater extent than is usual in engaging with the rod therebylessening their bite or grip and permitting the rod to move through oneor the other according to the direction of movement required in theoperation of raising the rod to form the are, or of feeding it downwardto compensate for combustion of the carbon. Asuitable grip or bite ofthe clutches upon the rod is secured by the springs Z, Z. The stops at,I), operate as in the arrangement shown in Fig. 10, to fully release therod when the lever L, is depressed.

In Fig. 12, the preferred form of lower or negative electrode E, isshown. This electrode is designed principally for use in cases where itis desired to make it unnecessary to metal such for instance as coppermade preferably conical near its top and terminating in a point of somerefractory material, such as iridium. The hollow body has severalopenings to permit the circulation of cooling currents of air. Its widthand external surface are made considerable in order to assist in keepingthe electrode cool.

It is sometimes desirable especially where the devices shown in Figs. 8and 9, are not used, and where the mass of the lever L, and that of thecore or armature O, is small, so that they possess little inertia, torender the magnet M, somewhat sluggish in its action, which is done bysurrounding its core with a copper band or tube forming a closed circuitconductor. Such closed circuit conductor might be formed of wire orconstructed in any other way. The secondary currents developed in thisconductor on opening and closing of the de-energizing or shunt brancharound the magnet serve to retard the magnetic changes of the core andthus prevent oscillation of the carbon rod. A closed circuit conductorsuitable for this purpose is indicated at B, Fig. 13.

The magnet M, may be employed for the purpose of producing the feed, theseparation of the carbons to form the are being effected by a separatemagnet. Such an arrangement is illustrated in Fig. 14, where aseparating magnet M, M, similar to that shown in United States PatentNo. 220,508, granted to E. Thomson, and E. J. Houston, is shown as theone for effecting the separation of the carbons by lowering the negativeelectrode E, and holding it down during the operation of the lamp. Theupper carbon is fed downward by the magnet M, connected with andoperating upon clutch devices in the manner already explained.

What I claim as my invention is- 1. The combination in an electric arclamp, of an electro magnet, a positive-feed clutch mechanism actuated bysaid magnet and arranged to feed the carbon by positive action on areverse movement of said magnets parts due to decrease of power in thesame, a circuit closer or controller connected to the circuit of saidmagnet,a derived circuit magnet for throwing the same into position toput the circuits of the feed magnet into operative condition when thearc increases in length, and a second circuit controller for the feedelectro magnet actuated thereby and arranged in the manner described soas to cause the magnet to be de-energized when the armature of the sameis raised by the magnets power, as and for the purpose described.

2. The combination substantially as described of the main circuit magnetand a following or yielding contact which serves in closing and openinga circuit to throw the magnet into and out of action, an operatingarmature for the contact having a range of movement beyond thatnecessary to merely open and close the circuit of said magnet, apositive or step by step feed mechanism operated by said magnet, acircuit closer for closing the connections of the contact, and a derivedcircuit magnet for actuating the circuit closer when the arc lengthens,as and for the purpose described.

3. The combination in an electric arc lamp, of an electro magnet, a feedmechanism operated thereby,a switch contact governed by the magnet forthrowing the same into and out of action so as to produce areciprocating movement of the parts, and a consequent step by step feed,and a closed circuit conducting band or envelope for said magnet.

4. The combination in an electric arc lamp, of a main circuit magnet,differentially moving feed clutches supported thereby, a deenergizingcircuit, a contact operated by said magnet and thrown, by the variationof the power of the magnet, into and out of position where thetie-energizing circuit may be completed, a second contact, and a derivedcircuit magnet for moving the same into position for completing thede-energizing circuit when the arc increases in length.

5. The combination with a carbon rod or carrier, of the differentiallypositively acting clamps bearing on the carbon rod or carrier atopposite sides thereof and moving positively in the same direction underthe action of the magnet or its retractor, said clamps being arranged toengage the carbon rod in substantially the same transverse line.

6. The combination with the carbon rod or carrier, of the two clampingshoes J, J, bearing against the carbon rod or carrier at opposite sidesthereof and moving positively in the same direction under the action ofthe magnet or its retractor, said clamping shoes being supported atdifferent distances from the fulcrum of the actuating lever, as and forthe purpose described.

7. The combination with the carbon rod or carrier, of differentiallymoving clamps both applied to tend to move the carbon in the samedirection at the same time, one of said clamps, to Wit: that having thegreater range of movement in a direction to feed the carbon having agreater bite or hold upon the carbon or carbon rods.

8. The combination in an electric arc lamp, of a main circuit magnet, apositive-feed mechanism engaging with the carbon carrier and supportedby said magnet, a de-energizing circuit, a contact operated by saidmagnet and thrown, by the variations of the power of the magnet, intoand out of position where the de-energizing circuit may be completed, asecond contact, and a derived circuit magnet for moving the same intoposition for completing the de-energizing circuit when the arc increasesin length.

Signed at Lynn, in the county of Essex and State of Massachusetts, this26th day of June, A. D. 1886.

ELIHU THOMSON.

Witnesses:

M L. THOMSON, GEORGE J. CARR.

